API 2510: Design and Construction of LPG Installations

By Authority Of THE UNITED STATES OF AMERICA Legally Binding Document

By the Authority Vested By Part 5 of the United States Code § 552(a) and Part 1 of the Code of Regulations § 51 the attached document has been duly INCORPORATED BY REFERENCE and shall be considered legally binding upon all citizens and residents of the United States of America. HEED THIS NOTICE: Criminal penalties may apply for noncompliance. e

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Official Incorporator: THE EXECUTIVE DIRECTOR OFFICE OF THE FEDERAL REGISTER WASHINGTON, D.C. Design and Construction of LPG Installations

Downstream Segment

API STANDARD 2510 EIGHTH EDITION, MAY 2001

American Petroleum Institute

Helping You Get The Job Done Right~M SPECIAL NOTES

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This standard provides minimum requirements for the design and constmction of installa tions for the storage and handling of liquefied petroleum gas (LPG) at marine and pipeline terminals, natural gas processing plants, refineries, petrochemical plants, and tank farms. This standard takes into consideration the specialized training and experience of operating personnel in the type of installation discussed. In certain instances, exception to standard practices are noted and alternative methods are described. This standard does not include information on the production or use of liquefied petro leum gas. h is not intended that this standard be retroactive or that it take precedence over contrac tual agreements. Wherever practicable, existing codes and manuals have been used in the preparation of this standard. This standard requires the purchaser to specify certain details and features. Although it is recognized that the purchaser may desire to modify, delete, or amplify sections of the stan dard, it is strongly recommended that such modifications, deletions, and amplifications be made by supplementing this standard rather than by rewriting or incorporating sections of this standard into another complete standard. API standards are published as an aid to procurement of standardized equipment and materials. These standards are not intended to inhibit purchasers or producers from purchas ing or producing products made to specifications other than those of API. API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict. Suggested revisions are invited and should be submitted to the standardization manager, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.

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CONTENTS

Page

SCOPE ...... 1.6 Retroactivity ...... 1.7 Characteristics of LPG ...... 1.8 Safety ......

2 REFERENCED PUBLICATIONS ......

3 TERMS AND DEFINITIONS ...... 2

4 DESIGN OF LPG VESSELS ...... 3 4.1 Applicable Design Construction Codes ...... 3 4.2 Design Pressure and Temperature...... 3 4.3 Design Vacuum ...... 3 4.4 Materials of Construction ...... 3 4.5 Vessel Connections ...... 3 4.6 Previously Constructed Vessels ...... 3

5 SITTING REQUIREMENTS AND SPILL CONTAINMENT...... 3 5.1 Siting ...... 3 5.2 Drainage ...... 5 5.3 Spill Containment ...... 5 5.4 Remote Impoundment ...... 5 5.5 Diking ...... 6

6 FOUNDATIONS AND SUPPORTS FOR LPG STORAGE VESSELS AND RELATED PIPING ...... 6 6.1 Applicable Codes and Specifications ...... 6 6.2 Special Requirements ...... 6

7 TANK ACCESSORIES, INCLUDING PRESSURE AND VACUUM-RELIEVING DEVICES ...... 8 7.1 Mandatory Equipment...... 8 7.2 Tank Accessory Materials...... 10

8 PIPING REQUIREMENTS ...... 10 8.1 American Society of Mechanical Engineers Code for Pressure Piping...... 10 8.2 LPG Piping ...... 10 8.3 Fittings...... 10 8.4 Plugs...... 10 8.5 Unions...... I I 8.6 Valves...... I I 8.7 Location, Installation, and Flexibility of Piping, Valves, and Fittings...... II

9 LOADING, PRODUCT TRANSFER, AND UNLOADING FACILITIES ...... II 9.1 Scope ...... II 9.2 Rates of Loading and Unloading ...... II 9.3 Transfer, Loading, and Unloading Equipment ...... 12 9.4 Grounding and Bonding ...... 12 9.5 Hose and Other Flexible Connectors for Product Transfer...... 13

v Page

9.6 Blowdown or Venting of Loading and Unloading Lines ...... 13 9.7 Marking of Valves in Loading and Unloading Systems ...... 13 9.8 Metering Equipment Used in Loading and Unloading ...... 13 9.9 LPG Odorization ...... 13

10 FIRE PROTECTION ...... 13 10.1 General...... 13 10.2 Access for Fire Fighting...... 13 10.3 FireWater Use ...... 14 lOA Fire Detection Systems ...... 15 10.5 Fire Extinguishers ...... 15 10.6 Fire-Fighting Foam ...... 16 10.7 Fireproofing of LPG Vessels ...... 16 10.8 Fireproofing of Structural Supports...... 16 10.9 Burying and Mounding ...... 16 10.10 Electrical Installations and Equipment...... 16 10.11 Critical Wiring and Control Systems ...... 16 10.12 Safety Precaution Signs...... 17 10.13 Lighting ...... 17 10.14 Fencing ...... 17 10.15 Roadways ...... 17

II REFRIGERATED STORAGE ...... 17 II. I General...... 17 I 1.2 Design Requirements ...... 17 11.3 Siting Requirements...... 17 IIA Thermal Considerations...... 18 I 1.5 Tank Accessories ...... 18 I 1.6 Piping Requirements ...... 19 11.7 Refrigeration System ...... 19

APPENDIX A PIPING, VALVES, FITTINGS, AND OPTIONAL EQUIPMEN ...... 21

Table I Minimum Horizontal Distance Between Shell of Pressurized LPG Tank and Line of Adjoining Property That May Be Developed ...... 4 Design and Construction of LPG Installations

1 Scope pressure, LPG is readily converted into the gaseous phase at normal ambient temperature. This standard covers the design, construction, and location of liquefied petroleum gas (LPG) installations at marine and 1.8 SAFETY pipeline terminals, natural gas processing plants, refineries, petrochemical plants, or tank farms. This standard covers The safety of LPG storage installations is enhanced by the storage vessels, loading and unloading systems, piping, or employment of good engineering practices, such as those rec and related equipment. ommended by this standard, during design and construction. 1.1 The size and type of the installation; the related facili ties on the site; the commercial, industrial, and residential 2 Referenced Publications population density in the surrounding area; the terrain and cli The most recent edition or revision of each of the following mate conditions; and the type of LPG handled shall be con manuals, codes, recommended practices, publications, stan sidered. Generally speaking, the larger the installation and the dards, and specifications shall form a part of this standard to greater the population density of the surrounding area, the the extent specified: more stringent are the design requirements. API 1.2 Design and construction considerations peculiar to RP 500 Class(fication of Locations for Electrical refrigerated storage, including autorefrigerated storage, are Installations at Petroleum Facilities covered in Section 9 of this standard. RP 505 Recommended Practice for Classification 1.3 In this standard, numerical values are presented with of Locations for Electrical Illstallations at U.S. customary units only. These U.S. customary values are Petroleum Facilities Classified as Class I, to be regarded as the standard values. Zone 0, Zone J and Zone 2 RP 520 Sizillg, Selection, and Installation qf Pres 1.4 This standard shall not apply to the design, construc sure-Relieving Devices ill Refineries tion, or relocation of frozen earth pits, underground storage RP521 Guide for Pressure-Relieving and Depres caverns or wells, underground or mounded storage tanks, and suring Systems aboveground concrete storage tanks. RP550 Manual on Installation of Refinery Instru 1.5 This standard does not apply to the following installa ments and Control Systems (out of print) tions: RP551 Process Measurement Instrumentation Std 607 Fire Test for So/i-Seated Quarter-Turn a. Those covered by NFPA 58 and NFPA 59. Valves b. U.S. Department of Transportation (DOT) containers. Std 620 Design and Construction o/Large, Welded, c. Gas utility company facilities; refinery process equipment; Low-Pressure Storage Tanks refinery and gas plant processing equipment; and transfer sys RP752 Management of Hazards Associated with tems from process equipment upstream LPG storage. Location of Process Plant Buildings, CMA d. Those tanks with less than 2000 gallons of storage Manager's Guide capacity. RP 1102 Steel Pipelines Crossing Railroads and Highways 1.6 RETROACTIVITY Std 2000 Venting Atmospheric and Low-Pressure The provisions of this standard are intended for application Storage Tanks: Nonrefrigerated and to new installations. This standard can be used to review and Refrigerated evaluate existing storage facilities. However, the feasibility of RP 2003 Protection Against Ignitions Arising Out of applying this standard to facilities, equipment, stmctures, or Static, Lightning, and Stray Currents installations that were already in place or that were in the pro Publ2218 Fireproq/ing Practices in Petroleum and cess of constmction or installation before the date of this pub Petrochemical Processing Plants lication, must be evaluated on a case-by-case basis Publ 251 OA Fire Protection Considerations for the considering individual circumstances and sites. Design and Operation of Liquefied Petro lellin Gas (LPG) Storage Facilities 1.7 CHARACTERISTICS OF LPG Spec 6FA Specification for Fire Testfor Valves LPG is customarily handled in a liquid state achieved by its Manual of Petroleum Measurement Standards, Chapter 5, liquefaction under moderate pressure. Upon release of the "Metering" 2 API STANDARD 2510

ACII 3 Terms and Definitions 318 Building Code Requirements for Rein forced Concrete Some of the terms used in this standard are defined in 3.1 through 3.13. AISC2 Specification for Structural Steel Buildings 3.1 aboveground tank or aboveground vessel: a tank or vessel all or part of which is exposed above grade. ASME3 B16.9 Factory-Made Wrought Steel Buttwelding 3.2 autorefrigeration: the chilling effect of vaporization Fittings of LPG when it is released or vented to a lower pressure. B31.3 Chemical Plant and Petroleum Re.finery Piping 3.3 boiling-liquid expanding-vapor explosion (BLEVE): the phenomenon of a pressurized LPG tank failing B31.4 Liquid Tran~portation Systems for Hydro carbons, Liquid Petroleum Gas, Anhydrous such as can occur from direct exposure to a fire (normally a Ammonia, and Alcohols catastrophic event). Section II, "Materials"; Boiler and Pressure Vessel Code, 3.4 installations: tanks, vessels, pumps, compressors, and Section VIII, "Pressure Vessels" accessories, piping, and all other associated equipment DoT4 required for the receipt, transfer, storage, and shipment of Tramportation Sq/ety Act ()/1974, Part 173, Section 315 LPG.

ICB05 3.5 liquefied petroleum gas (LPG or LP-gas): any Un(/orm Building Code material in liquid form that is composed predominantly of NFPA6 any of the following hydrocarbons or of a mixture thereof: 30 Flammable and Combustible Liquids Code propane, propylene, butanes (normal butane or isobutane), 58 Storage and Handling ()/ Lique.fied Petro and butylenes. leum Gases 3.6 mounded tank or mounded vessel: a tank or ves 59 Storage and Handling of Liquefied Petro sel located above or partially above the general grade level leum Gases at Utility Gas Plants but covered with earth, sand, or other suitable material. 59A Production, Storage (Ind Handling ()/ Liq uefied Natural Gas (LNG) 3.7 refrigerated storage: storage in a vessel or tank arti 70 National Electrical Code ficially maintained at a temperature below the nominal ambi ent temperature. NPGA7 Bul128 Protection o/Tramfer Areas 3.8 rollover: the spontaneous and sudden movement of a UL8 large mass of liquid from the bottom to the top surface of a 1709 Rapid Rise Fire Tests ()/ Protection Materi refrigerated storage reservoir due to an instability caused by alsfor Structural Steel an adverse density gradient. Rollover can cause a sudden pressure increase and can affect vessel integrity. iAmerican Concrete Institute, P. O. Box 19150, Detroit, Michigan 3.9 shall: indicates provisions that are mandatory. 48219-0 I SO. 2American Institute of Steel Construction, One East Wacker Drive, 3.10 Use of the term shall consider directly before a Suite 3100, Chicago, Illinois 60601-200 I. 'American Society of Mechanical Engineers, 345 East 47th Street, design or construction factor (such as a force or safety) indi New York, New York 10017. cates that the factor's effects and significance shall be evalu 4U.S. Depal1ment of Transportation. The act is available from the ated using good engineering judgement-through an U.S. Government Printing Office, Washington, D.C. 20402. examination or test if appropriate-and the design mayor may 51nternational Conference of Building Officials, 5360 Workman Mill Road, Whittier, California 90601-2298. not be adjusted accordingly. 6National Fire Protection Association, I Batterymarch Park, Quincy, Massachusetts 02269-910 I. 3.11 tank or vessel: a container used for storing LPG. 7National Propane Gas Association, 1600 Eisenhower Lane, Suite 100, Lisle, Illinois 60532. 3.12 underground tank or underground vessel: a 8Underwriters Laboratories, 333 Pfingsten Road, Northbrook, Illi tank or vessel all parts of which are completely buried below nois 60062-2096. the general grade of the facility. DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 3

4 Design of LPG Vessels ambient temperature. In this situation, no additional protec tion against vacuum is needed. 4.1 APPLICABLE DESIGN CONSTRUCTION b. Design for partial vacuum with a vacuum relief valve and CODES a connection to a reliable supply of hydrocarbon gas. This 4.1.1 Vessels shall meet the requirements of the ASME alternative may compromise product quality. Boiler and Pressure Vessel Code, Section VIII, Division I or 2. c. Design for partial vacuum with a vacuum relief valve that admits air to the vessel. This alternative, under some condi 4.1.2 When complete rules for any specific design are not tions, may present a hazard from the presence of air in the given, the manufacturer, subject to the approval of the pur LPG storage vessel, and this hazard shall be considered in the chaser, shall provide a design as safe as would be provided in design. the currently applicable code listed in 4.1.1. 4.4 MATERIALS OF CONSTRUCTION 4.2 DESIGN PRESSURE AND TEMPERATURE 4.4.1 All materials of construction shall meet the require 4.2.1 The design pressure of LPG vessels shall not be less ments of Section II of the ASME Boiler and Pressure Vessel than the vapor pressure of the stored product at the maximum Code. product design temperature. The additional pressure resulting 4.4.2 Low-melting-point materials of construction, such as from the partial pressure of noncondensable gases in the vapor aluminum and brass, shall not be used for LPG vessels. space and the hydrostatic head of the product at maximum fill shall be considered. Ordinarily, the latter considerations and 4.5 VESSEL CONNECTIONS the performance specifications of the relief valve require a dif ferential between design pressure and maximum product 4.5.1 The number of penetrations in any vessel shall be vapor pressure that is adequate to allow blow down of the pres minimized, particulary those located below the working liq sure relief valve (see API RP 520). uid level (i.e., below the vapor space).

4.2.2 Both a minimum design temperature and a maximum 4.5.2 Flange connections shall be a minimum of ASME design temperature shall be specified. In determining a maxi Class 150. All fittings shall be a minimum of NPS Y4. mum design temperature, consideration shall be given to fac 4.5.3 Refer to Section 8 for piping requirements. tors such as ambient temperature, solar input, and product run down temperature. In determining a minimum design temper 4.6 PREVIOUSLY CONSTRUCTED VESSELS ature, consideration shall be given to the factors noted in the API 510 shall be used where an existing vessel is to be preceding sentence as well as the autorefrigeration tempera relocated or reused in a new service. ture of the stored product when it flashes to atmospheric pres sure. ASME Section VIII, Division I, has special rules for conditions where reduced temperature, as a result of autore 5 Sitting Requirements and Spill frigeration or ambient temperature, is caused by coincident Containment with a reduction in pressure. In such case it is required to 5.1 SITING evaluate the material (by impact testing if necessary) at the temperature of the product corresponding to a pressure that 5.1.1 General stresses the vessel shell to approximately 10% of the ultimate 5.1.1.1 Site selection is meant to minimize the potential tensile strength of the shell material. When the vessel is risk to adjacent property presented by the storage facility and repressurized, this must be done slowly to allow the tempera the risk presented to the storage facility by a fire or explosion ture to increase as the pressure is increased. on adjacent property. The following factors shall be consid ered in site selection: 4.3 DESIGN VACUUM a. Proximity to populated areas. LPG vessel design shall consider vacuum effects and be b. Proximity to public ways. designed accordingly. Where an LPG vessel is not designed c. Risk from adjacent facilities. for full vacuum, some alternatives, in order of preference, are d. Storage quantities. as follows: e. Present and predicted development of adjacent properties. a. Design for partial vacuum condition. This alternative is f. Topography of the site, including elevation and slope. applicable when the vacuum conditions caused by ambient g. Access for emergency response. temperature conditions. The design pressure shall be equal to h. Availability of needed utilities. the minimum vapor pressure of the product at the minimum \. Requirements for the receipt and shipment of products. 4 API STANDARD 2510 j. Local codes and regulations. The minimum horizontal distance between shells need not k. Prevailing wind conditions. exceed 200 ft.

A more likely LPG incident, and in the context of this pub 5.1.2.4 The mlI11mUm horizontal distance between the lication a more relevant one, is leakage from piping or other shell of an LPG tank and a regularly occupied building shall components attached to or near the vessel followed by igni be as follows: tion, a flash fire or vapor cloud explosion, and a continuing pool fire and pressure (torch) fire. a. If the building is used for the control of the storage facility, 50 ft. 5.1.1.2 With the exception of spacing, the design features b. If the building is used solely for other purposes (unrelated discussed in this standard are intended to prevent a major to control of the storage facility), 100 ft. incident. Spacing is intended to minimize both the potential c. Compliance with API 752 may be used in lieu of the for small leak ignition and the exposure risk presented to requirements in paragraph a and b. adjacent vessels, equipment, or installations in case ignition occurs. Spacing is not intended to provide protection from a 5.1.2.5 The minimum horizontal distance between the major incident. shell of an LPG tank and facilities or equipment not covered in 5.1.2.1 through 5.1.2.4 shall be as follows: 5.1.1.3 Safety analysis and dispersion modeling are useful tools in estimating setback distances to limit the exposure risk a. For process vessels, 50 ft. to adjacent facilities. b. For flares or other equipment containing exposed flames, 100 ft. 5.1.2 Minimum Distance Requirement c. For other fired equipment, including process furnaces and 5.1.2.1 The minimum horizontal distance between the utility boilers, 50 ft. shell of a pressurized LPG tank and the line of adjoining d. For rotating equipment, 50 ft; except for pumps taking property that may be developed shall be as shown in Table l. suction from the LPG tanks, 10 ft. Where residences, public buildings, places of assembly, or e. For overhead power transmission lines and electric substa industrial sites are located on adjacent property, greater dis tions, 50 ft. In addition, siting shall be such that a break in the tances or other supplemental protection shall be provided. overhead lines shall not cause the exposed ends to fall on any vessel or equipment. 5.1.2.2 The minimum horizontal distance between the f. For loading and unloading facilities for trucks and railcars, shells of pressurized LPG tanks or between the shell of a 50 ft. pressurized LPG tank and the shell of any other pressurized hazardous or flammable storage tank shall be as follows: g. For navigable waterways, docks, and piers, 100 ft. h. For stationary internal combustion engines, 50 ft. a. Between two spheres, between two vertical vessels, or between a sphere and a vertical vessel, 5 ft or half of the 5.1.2.6 The minimum horizontal distance between the shell diameter of the larger vessel, whichever is greater. of an LPG tank and the edge of a spill containment area for b. Between two horizontal vessels, or between a horizontal flammable or combustible liquid storage tanks shall be 10 ft. vessel and a sphere or vertical vessel, 5 ft or three quarters of Note: If the spill containment is by the use of dikes or walls, the edge the diameter of the larger vessel, whichever is greater. of the spill containment area for the purpose of spacing is defined as the centerline of the dike or wall. If the spill containment is by slop 5.1.2.3 The minimum horizontal distance between the ing, grading, or channels, the edge of the spill containment area for shell of a pressurized LPG tank and the shell of any other the purpose of spacing is defined as the outer edge of the wetted area nonpressurized hazardous or flammable storage tank shall be at the design incident for the spill containment facility. the largest of the following with the exception noted after Item d: Table 1-Minimum Horizontal Distance Between a. If the other storage is refrigerated, three quarters of the Shell of Pressurized LPG Tank and Line of Adjoining greater diameter. Property That May Be Developed b. If the other storage is in atmospheric tanks and is designed Water Capacity of Each Minimum to contain material with a flash point of 100°F or less, one Tank (gallons) Distance (feet) diameter of the larger tank. 2,000-30,000 50 c. If the other storage is in atmospheric tanks and is designed 30,001-70,000 75 to contain material with a flash point greater than 100°F, half 70,001-90,000 100 the diameter of the larger tank. 90,001-120,000 125 d. 100 ft. 120,00 I or greater 200 DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 5

5.1.3 Siting of Pressurized LPG Tanks and a. The effects of thermal shock associated with spilling LPG Equipment (such as shock resulting from the autorefrigeration temperature ). 5.1.3.1 Pressurized LPG tanks shall not be located within buildings, within the spill containment area of flammable or b. Provision of adequate venting of the vapor generated dur combustible liquid storage tanks as defined in NFPA 30, or ing an LPG spill. within the spill containment area for refrigerated storage tanks. 5.3.3 If spill containment is to be provided, it shall be by 5.1.3.2 Compressors and pumps taking suction from the remote impoundment of spilled material or by diking of the LPG tanks should not be located within the spill containment area surrounding the vessel. The containment area shall not area of any storage facility unless provisions are made protect contain any other equipment, except as permitted by this the storage vessel from the potential fire exposure. Examples standard. of such examples include (a) a submerged-motor, direct-cou 5.3.4 If the floor of any spill containment area will not pled pump with no rotating element outside of the pump con allow rainwater to dissipate within 24 hours, a drainage sys tainment vessel; (b) a submersible pump inside an LPG tank. tem shall be installed. Any drainage system provided shall 5.1.3.3 Horizontal LPG tanks with capacities of 12,000 include a valve or shear gate located in an accessible position gallons or greater shall not be formed into groups of more outside the spill containment area. The valve or shear gate than six tanks each. Where multiple groups of horizontal LPG shall normally be kept closed. The drainage system shall be vessels are to be provided, each group shall be separated from one of the following types: adjacent groups by a minimum horizontal shell-to-shell dis a. A vapor sealed catch basin within the spill containment tance of 50 ft. area discharging to a closed drainage system outside the spill Note: Horizontal vessels used to store LPG should be oriented so containment area. that their longitudinal axes do not point toward other facilities (such b. A pipe through the dike or wall discharging to a drainage as containers, process equipment, control rooms, loading or unload ing facilities, or flammable or combustible liquid storage facilities or system outside the spill containment area. offsite facilities located in the vicinity of the horizontal vessel). The drainage system shall keep the contents of the tank from entering natural water courses and from entering sys 5.2 DRAINAGE tems incapable of safely containing LPG. 5.2.1 The ground under and surrounding a vessel used to store LPG shall be graded to drain any liquid spills to a safe 5.4 REMOTE IMPOUNDMENT area away from the vessel and piping. The grading shall be at 5.4.1 If remote impoundment is to be used for spill con a slope of at least 1%. tainment, the remote impoundment facility shall be designed 5.2.2 The drainage system shall be designed to prevent liq according to the requirements given in 5.4.2 through 5.4.5. uid spilled from one tank from flowing under any other tank and shall minimize the risk to piping from spilled LPG. 5.4.2 Grading of the area under and surrounding the ves sels shall direct any liquid leaks or spills to the remote 5.2.3 The spill drainage area shall not contain equipment, impoundment area. Grading shall be at a minimum of 1% except as permitted by this standard. slope.

5.2.4 Walls, dikes, trenches, or channels are permitted to 5.4.3 The use of walls, dikes, trenches, or channels to facil assist in draining the area. itate the draining of the area is permitted. 5.3 SPILL CONTAINMENT 5.4.4 The remote impoundment area shall be located at least 50 ft from the vessels draining to it and from any hydro 5.3.1 Spill containment shall be considered for all locations carbon piping or other equipment. and provided in locations in which either of the following conditions will result in a significant hazard: 5.4.5 The holdup of the remote impoundment area shall be at least 25% of the volume of the largest vessel draining to it. a. The physical properties of the stored LPG make it likely If the material stored in the vessel has a vapor pressure that is that liquid LPG will collect on the ground. (This would be the less than 100 psia at 100°F, the holdup for the remote case if the LPG is a mixture of butane and pentane.) impoundment facility shall be at least 50% of the volume of b. Climatic conditions during portions of the year make it the largest vessel draining to it. Larger holdUps shall be pro likely that liquid LPG will collect on the ground. vided in the remote impoundment facility at locations where 5.3.2 The following shall be considered in the selection of the expected vaporization is less than that indicated by the materials for all components- including structural supports material's vapor pressure because of climatic conditions or -of a spill containment facility: the physical properties of the material. 6 API STANDARD 2510

5.5 DIKING vessels and related piping shall meet the requirements stipu lated in the following codes and specifications: 5.5.1 If diking around the vessel is to be used for spill con tainment, the diked area shall be designed according to the a. For concrete, ACI 318. requirements given in 5.5.2 through 5.5.7. b. For masonry, ICBO Uniform Building Code. 5.5.2 Grading of the area under and surrounding the ves c. For structural steel, AISC Specification for Structural Steel sels shall direct any liquid leaks or spills to the edge of the Buildings. diked area. Grading shall be at a minimum of I % slope. Where applicable local codes are more stringent, the local Within the diked area, grading should cause spills to accumu codes shall apply. late away from the vessel and any piping located within the diked area. 6.2 SPECIAL REQUIREMENTS 5.5.3 If an LPG sphere is diked, each sphere shall be pro vided with its own diked area. If LPG is stored in horizontal 6.2.1 General vessels, a single diked area may serve a group of tanks, as The foundation and supports shall conform to the provi defined in 5.1.3.3. sions set forth in 6.2.2 through 6.2.15. 5.5.4 The holdup of the diked area shall be at least 25% of the volume of the largest vessel within it. If the material 6.2.2 Materials stored in the vessel has a vapor pressure that is less than 100 Supporting structures shall be made of one or a combina psia at 100°F, the holdup for the diked area shall be at least tion of the following materials: 50% of the volume of the largest vessel within it. Larger hold ups shall be provided in the diked area at locations where the a. Reinforced masonry. expected vaporization is less than that indicated by the mate b. Reinforced concrete. rial's vapor pressure because of climatic conditions or the c. Steel plate, pipe, or structural shapes. physical properties of the material. Note: Larger holdups may also be provided when more than one 6.2.3 Soil Information vessel is located within the same diked area. The design of the foundation shall be based on a thorough 5.5.5 When dikes or walls are used as part of the spill con knowledge of the load-bearing capacity and settlement prop tainment system, the minimum height of a dike or wall con erties of the soil. Where information regarding soil conditions structed of earth shall be 1.5 ft and the minimum height of a is not available, an investigation shall be conducted. dike or wall constructed of concrete, masonry, or another ero sion-resistant material shall be I ft. Provisions shall be made 6.2.4 Settlement of Foundation for normal and emergency access into and out of the diked enclosure. Where dikes must be higher than 12 ft or where ven The size and depth of the foundation shall be designed to tilation is restricted by the dike, provision shall be made for limit settlement of the vessel to prevent excessive stresses in normal operation of valves and access to the top of the tank or the tank and connected piping. tanks without the need for personnel to enter into the area of the diked enclosure that is below the top of the dike. All earthen Note: Settlement should be monitored during the hydrotes!. dikes shall have a flat top section not less than 2 ft wide. 6.2.5 Bottom of Foundation 5.5.6 Any dike or wall enclosure used for LPG contain ment shall include adequate access provisions (such as stairs The bottom of the foundation shall be below the frost line for personnel and ramps for vehicles, if required), shall be and below nearby sewers or lines having the potential for designed to permit its free ventilation, and shall be con leakage or washout that could result in settlement of the structed to retain the spilled liquid. Enclosures shall be foundation. designed to prevent unauthorized access by motor vehicles. 6.2.6 Floating Foundation or Piling

6 Foundations and Supports for LPG Where it is impracticable to design foundations for normal Storage Vessels and Related Piping settlement as described in 6.2.4, a floating foundation or pil ing is permitted. In this case, the settlement indicated by soil 6.1 APPLICABLE CODES AND SPECIFICATIONS tests shall be used for design, and the settlement measured The materials, principles, methods, and details of design during subsequent service shall be used to check for adequate and construction of foundations and supports for LPG storage flexibility in connected piping. DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 7

6.2.7 Loads on Supporting Structure 6.2.11 Saddles

The following loads shall be considered in the design of 6.2.11.1 When a horizontal tank is supported by saddles, the supporting structure: the features specified in 6.2.11.2 through 6.2.11.5 shall be a. Static loads during erection plus expected wind, ice, and incorporated in the design. snow loads during the erection. 6.2.11.2 Two piers shall be used to support horizontal b. Static loads during water testing plus 25% of the wind, ice, vessels. and snow loads. c. Static loads during operation (including the load due to 6.2.11.3 Consideration shall be given to the placement of fireproofing) plus applicable combinations of wind, ice, snow, supports to obtain the most desirable stress distribution in the and earthquake loads. vessel shell. d. Loads resulting from expansion and contraction of the 6.2.11.4 The shape of the saddles shall conform to the fab vessel due to internal pressure and temperature changes. ricated shape of the vessel or to the steel pad attached to the e. Loads resulting from differential settlement across the vessel. supporting structures and foundations. f. Static and dynamic loads during maintenance and 6.2.11.5 Doublers or reinforcing plates may be installed operations. between the vessel shell and the supports to avoid external corrosion of the shell, provide for wear caused by tempera 6.2.8 Support Design ture-induced movement, or reduce the stress in the shell at the 6.2.8.1 The design of supports for vessels shall include support points. If such plates are used, they shall be continu provisions for expansion and contraction of the vessel due to ously welded to the vessel shell after any free moisture is internal pressure and temperature change of the vessel shell. removed from under the plates. A threaded weep hole shall be provided at the low point of each plate. Where corrosion 6.2.8.2 Flexibility shall be provided in the attached piping plates are used, the plates shall extend beyond the limits of to avoid imposing excessive stress on vessel nozzles and associated piping as a result of vessel movement. the supporting saddles to aid in distributing the support loads. The thickness of corrosion plates shall not be included in cal Note: The following publication contains additional material regard culating the stress at the hom of the saddle. ing the design of supports: Section VIII of the ASME Boiler and Pressure Vessel Code. 6.2.12 Multiple Vessels 6.2.8.3 Pressure retaining portions of storage vessels 6.2.12.1 Continuous footings may be used for multiple should typically not contact concrete or masonry supports or vessel installations. In such instances, the loading of footings concrete or masonry fireproofing, since these contact points shall be calculated for various probable combinations of may be sites for external corrosion. If such contact points are loads, such as the load that occurs when adjacent vessels are present, they should be identified for routine inspection. full and the load that occurs when alternate vessels are full.

6.2.9 Vessel Shell Loads 6.2.12.2 Continuous piers shall not be used for multiple In the design of vessel supports, special attention shall be vessel installations without the incorporation of special drain given to the loads imposed on the vessel shell. Consideration age provisions. shall be given to the following: 6.2.13 Anchorage a. Secondary forces resulting from service temperatures or changes in temperatures. 6.2.13.1 In areas where there is a risk of flooding, the ves b. Test and operating pressures. sel shall be anchored to the foundation or support to prevent c. Liquid loads, both with and without pressure applied. floating in case of a flood. Anchorage shall not restrict vessel d. Loads due to piping reactions. movements resulting from expansion and contraction of the e. Normal supporting loads. vessel due to temperature changes and internal pressure. f. Loads due to liquid sloshing (in earthquake zones). 6.2.13.2 Anchorage of the vessel to the foundation or sup 6.2.10 Diagonal Members port shall be provided to resist wind and earthquake loads and to control temperature-induced movement. Diagonal members, such as those used for bracing vertical columns, shall not be attached directly to a vessel unless ade 6.2.13.3 Anchorage to the foundation or support shall be quate provisions are made for the resulting loads in the design provided to resist any uplifting forces resulting from internal of the vessel. pressure in the tank or vessel. 8 API STANDIIRD 2510

6.2.14 Vertical Tank Skirts any thermal expansion that may occur after filling is com pleted. The maximum filling height shall be set so that when a 6.2.14.1 Where vertical vessels are supported by skirts, the tank filled to that level at the minimum anticipated storage skirts shall be provided with a single opening for inspection temperature the thermal expansion of the liquid will not cause or access. The opening shall be as small as practicable. the LPG level to exceed 98% of the liquid full level. 6.2.14.2 Skirt openings shall be reinforced when required to prevent buckling or overstressing of the skirt as a result of 7.1.4 Level Gauges imposed loads as covered in 6.2.7. Columnar glass level gauges shall not be used. Reflex and see-through level gauges shall be equipped with a ball check 6.2.15 Corrosion Protection valve or a similar protective device. 6.2.15.1 Steel supports and their members shall be posi tioned to prevent the accumulation of water. Where this posi 7.1.5 Pressure Gauge tioning is impractical, adequate drainage openings shall be On each tank, a suitable pressure gauge should be consid provided to prevent such accumulation. ered. When used it should be connected to the vapor space. 6.2.15.2 Enclosed spaces in which water might accumu late during construction or operation shall be provided with 7.1.6 Pressure- and Vacuum-Relieving Devices drainage openings. 7.1.6.1 General 7 Tank Accessories, Including Pressure Each tank shall be provided with one or more spring and Vacuum-Relieving Devices loaded or pilot-operated pressure relief valves. The pressure relief valve or valves shall be set to discharge as required by 7.1 MANDATORY EQUIPMENT the AS ME Code. Pilot-operated pressure relief devices shall be designed so that the main valve will open automatically 7.1.1 General and protect the tank if the pilot valve fails. Pilot-operated Tanks shall be fitted with the equipment described in 7.1.2 valves shall be provided with a backflow preventer if the pos through 7.1.8. Equipment shall be suitable for use with LPG sibility exists that the internal pressure can drop below atmo and designed for at least the maximum service conditions to spheric. Tanks that may be damaged by internal vacuum shall which it may be subjected. be provided with vacuum-relieving devices. Weight and lever pressure-relieving devices shall not be used. 7.1.2 Liquid-Level Gauging Equipment 7.1.6.2 Pressure Relief Valve Flow Capacities 7.1.2.1 Each LPG tank shall be provided with liquid-level gauging equipment as specified in 7.1.2.2 through 7.1.2.5. Pressure relief valves installed on LPG tanks shall be designed to provide adequate flow capacity to protect the tank 7.1.2.2 Each tank shall be equipped with a reliable level during fire exposure. Other causes of tank overpressure, such indicating system. The need for a second, independent level as overfilling and introduction of material with a higher vapor indicating system shall be determined by a safety analysis. pressure in a common piping system, shall be considered in 7.1.2.3 An independent high-level alarm shall be provided. determining design flow capacity. Pressure relief valves shall The alarm shall be set to give the operator sufficient time to be designed and sized in accordance with API RP 520, Part I, stop the flow before the maximum permissible filling height and RP 521. is exceeded (see 7.1.3). The alarm shall be located so that it is audible and visible to the operating personnel controlling the 7.1.6.3 Pressu re Relief Valve Information filling operation. Each pressure relief valve shall be marked as required by 7.1.2.4 For tanks that cannot be removed from service, the applicable AS ME code, API standard, or API recom provisions shall be included for testing, repairing, and replac mended practice. ing primary gauges and alarms while the tank is in service. 7.1.6.4 Pressure Relief Valve Installation 7.1.2.5 In tanks that have a high-level cutoff, the cutoff device shall be in addition to and independent of the high 7.1.6.4.1 Pressure relief valves shall be installed in accor level alarm specified in 7.1.2.3. dance with API RP 520, RP 521, and the requirements of 7.1.6.4.2 through 7.1.6.4.6. 7.1.3 Maximum Liquid Level 7.1.6.4.2 The pressure relief valve shall be installed to pro The maximum permissible filling height of an LPG tank vide direct connection to the vapor space and to minimize liq shall be set to provide adequate vapor space to accommodate uid carry-over during vapor relief, especially when the tank is DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 9 nearly full. This shall be achieved by locating the pressure 7.1.6.5.3 Discharge vents shall be protected against relief valve connections as close as practical to the top of the mechanical damage. vapor space. 7.1.6.5.4 If discharge vents rei ieve to the atmosphere, they 7.1.6.4.3 The possibility of tampering with the adjustment shall be designed to prevent entry of moisture and conden mechanism shall be minimized. If the adjustment mechanism sate. This design may be accomplished by the use of loose-fit is external, it shall be sealed. ting rain caps and drains. Drains shall be installed so that the discharge will not impinge on the tank or adjoining tanks, 7.1.6.4.4 The inlet and outlet piping for the pressure relief piping, equipment, and other structures. valve shall be designed to pass the rated capacity of the valve without exceeding the allowable pressure-drop limits. 7.1.6.5.5 Discharge vents shall be designed to handle any thrust developed during venting. Discharge shall not be less 7.1.6.4.5 The pressure relief system shall be protected than 3 m (10ft) above the operating platform. from the closure of any block valves installed between the tank and the pressure relief valve or between the pressure 7.1.6.5.6 Discharge shall be to an area that has the follow relief valve and its discharge vent outlet. This protection may ing characteristics: be achieved by one of the following procedures: a. The area prevents flame impingement on tanks, piping, a. Installing the pressure relief valve without block valves. equipment, and other structures. b. Providing excess pressure relief valve capacity with multi b. The area prevents vapor entry into enclosed spaces. way valves, interlocked valves, or sealed block valves c. The area is above the heads of any personnel on the tank, arranged so that isolating one pressure relief valve will not adjacent tanks, stairs, platforms, or the ground. reduce the capacity of the system to below the required relieving capacity. 7.1.6.6 Pressure Setting c. Locking or sealing the block valves open without install Pressure relief valves shall be tested for correct set pressure ing excess relieving capacity, as follows. The valve seals or before being placed in service. See API RP 520. locks should be checked routinely to assure they are in place and locks are operable. The valves shall be closed by an 7.1.7 Shutoff Valves authorized person who shall remain stationed in audible and 7.1.7.1 Shutoff valves shall conform to the criteria speci visual contact with the vessel, and in a position to correct or fied in 7.1.7.1.1 through 7.1.7.1.3. arrest potential overpressure events while the valves are closed and the tank is in operation and shall lock or seal the 7.1.7.1.1 Shutoff valves shall be provided for all tank con valves open before leaving. The authorized person shall be nections except the following: able to observe the operating pressure while the valves remain blocked and shall be ready to take emergency action if a. Connections on which safety valves are mounted. required. b. Connections containing a Ilk-inch-maximum restriction orifice, plugs, or thermometer wells. 7.1.6.4.6 The stem of any gate valve installed in the pres sure relief system shall be in a horizontal or below-centerline 7.1.7.1.2 Shutoff valves shall be located as close to the position. tank as is practical. The preferred location is at the shell noz zle. Shutoff valves shall be readily accessible for operation 7.1.6.5 Discharge Vents and maintenance.

7.1.6.5.1 Discharge vents from the pressure relief valves or 7.1.7.1.3 Shutoff valves shall conform to the material and construction requirements of 8.6. common discharge headers shall be designed to meet the requirements of API RP 520 and RP 521 and shall be 7.1.7.2 All shutoff valves located on nozzles below the installed in accordance with the requirements given in maximum liquid level shall be designed to provide a visual 7.1.6.5.2 through 7.1.6.5.6. indication of the valve position and shall be capable of main taining an adequate seal under fire conditions. Valves meeting 7.1.6.5.2 Discharge vents shall lead to the open air or to a the requirements of API Std 607 or Spec 6FA have the flare system. Discharging directly to the atmosphere is unac required fire resistance. ceptable if liquid LPG might be released into the atmosphere, unless the discharge is through thermal relief valves. Positive 7.1.7.3 When the capacity of the vessel exceeds 10,000 design and operational steps shall be taken to prevent the dis gallons, all shutoff valves on inlet and outlet piping located charge of liquid LPG from atmospheric vents. Such steps below the maximum liquid level shall either close automati include automatic shutdown of filling operations prior to cally or be remotely operable during the first 15 minutes of overfilling. fire exposure. This may require fireproofing of the control 10 API STANDARD 2510 system (see 10.11). These valves shall also be manually oper 8.2.3 Minimum Specifications able at the installed location. Check valves installed on dedi 8.2.3.1 The pipe wall thickness shall be equal to or greater cated fill lines are suitable for meeting the requirements of than that required by ASME 831.3. The minimum require this paragraph. ments specified in 8.2.3.2 and 8.2.3.3 shall also apply. 7.1.8 Temperature Indicator 8.2.3.2 Pipes made from materials subject to brittle-failure, such as carbon steel, shall have the following minimum wall Each tank shall be fitted with a suitable thermometer well. thicknesses:

7.2 TANK ACCESSORY MATERIALS a. Nominal pipe size less than NPS 2-Schedule 80. b. NPS 2-5-Schedule 40 (except for threaded connections, Ductile (nodular) iron, cast aluminum, malleable iron, which shall be Schedule 80). and brass shall not be used in any pressure-retaining tank c. NPS 6-wall thickness of 0.25 NPS. accessories. d. NPS 8-12-Schedule 20. e. NPS 14 or larger-Schedule 10. 8 Piping Requirements 8.2.3.3 Pipes made from materials not subject to brittle 8.1 AMERICAN SOCIETY OF MECHANICAL failure, such as stainless steel, shall have the following mini ENGINEERS CODE FOR PRESSURE PIPING mum wall thicknesses:

Piping at facilities covered under this standard shall con a. NPS 3/4 or less-Schedule 80S. form to the provisions of AS ME 831.3; except that piping b. NPS 1, ['/2, or 2-Schedule 40S. that falls under the exclusion provided in 300.1.3(e) of ASME c. NPS larger than 2-Schedule lOS. B31.3 shall be constructed in accordance with the provisions of ASME B31.4. The additional provisions of this section 8.2.4 Pressure Tubing apply to piping constructed in accordance with ASME B31.3. Tubing shall be constructed of steel. If tubing will be exposed to a corrosive atmosphere, stainless steel shall be 8.2 LPG PIPING used. 8.2.1 Recommended Pipe 8.3 FITTINGS Piping shall be seamless, electric-resistance-welded, or submerged-arc-welded pipe. Pipe to be used in piping appli 8.3.1 Butt-Welding Fittings cations of 2 in. or smaller shall be seamless. Butt-welding fittings shall be made from seamless steel or equivalent material, shall be of at least the same thickness and 8.2.2 Piping Joints schedule as the piping, and shall conform to ASME B 16.9. 8.2.2.1 The number of joints of any type between the ves sel and the first block valve shall be minimized. 8.3.2 Socket-Welding Fittings Socket-welding fittings 2 in. or smaller in size, such as 8.2.2.2 Welded joints shall be used where practical. elbows, tees, and couplings, shall be of forged steel and shall 8.2.2.3 The number of flanged joints shall be minimized. have a working pressure of at least 2000 psi. 8.2.2.4 Joints in pipe NPS 2 or larger shall be welded or 8.3.3 Packed-Sleeve and resilient-sealed flanged. Couplings 8.2.2.5 Joints in pipe smaller than NPS 2 shall be socket Packed-sleeve and resilient-sealed couplings shall not be welded, butt-welded, or flanged. used. 8.2.2.6 Piping gaskets shall be of the self-centering or con fined type and shall be resistant to LPG. 8.3.4 Flanges 8.2.2.7 Threaded connections shall be minmized to the Weld-neck flanges are preferred. Socket-weld NPS 2 and extent practicable and shall be between NPS 3/4 and NPS smaller are acceptable. If slip-on flanges are used, they shall I' /2, inclusive. be welded both inside and outside.

Note: Threaded connections are typically used for connections such 8.4 PLUGS as instrumentation and specialty devices and are downstream of a block valve. Plugs shall be constructed of steel. DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 11

8.5 UNIONS 8.7.3 All water drawoffs shall be extended so that they do not terminate under the vessel. Drain lines shall not be Unions shall be of forged steel, shall have a working pres sure of at least 3000 psi, and shall have ground metal-to-metal directed into a public sewer or into a drain not designed to seats. Gasket unions shall not be used. Unions shall not be contain flammable materials. Double valves shall be pro used between the vessel and the first valve. vided. When drain lines are supported by any type of support not directly attached to the tank, adequate flexibility shall be 8.6 VALVES provided in the lines to accommodate differential settlement. Stress imposed on the vessel nozzle by the drain lines shall be 8.6.1 Primary Shutoff Valves minimized. 8.6.1.1 The primary shutoff valves for a tank (specifically 8.7.4 Water drain lines and similar small lines shall be ade the valves nearest the vessel that can shut off flow) shall be quately supported or shall be fabricated with sufficient strength made from steel. Valves constmcted of free-machining steel to be self-supporting under operating conditions, including the similar to AISI Series 1100 and 1200 shall not be used. condition of maximum flow reaction thmst. Stress imposed on 8.6.1.2 Union or screwed-bonnet valves shall not be used the vessel by the drain lines shall be minimized. unless they are equipped with bonnet retainers or the bonnets are tack welded. 8.7.5 Freeze protection shall be considered for all drain lines and potential water collection points. Abnormal operat 8.6.1.3 Valves that are sandwiched between two flanges by ing conditions, such as might occur during abnormally cold long, exposed bolts shall not be used, unless the valves have weather, should be considered where water might collect and lug-type bodies that cover the bolts. freeze protection is needed. 8.6.1.4 Ball valves shall meet the requirements of API Std 607. 9 Loading, Product Transfer, and Unloading Facilities 8.6.2 Check Valves Check valves shall be installed on the discharge side of all 9.1 SCOPE centrifugal pumps. This section covers the design and construction of facilities that transfer LPG as follows: 8.6.3 Pressure Relief Valves a. From a pipeline to stationary storage. Pressure relief valves shall be constmcted of steel. b. From tmck or railcar racks and marine docks to stationary 8.6.4 Thermal Relief Valves storage. c. From stationary storage to truck or railcar racks or marine Suitable thermal relief valves shall be considered on liquid docks. lines that can be blocked between two shutoff valves. Other equipment that can be blocked between shutoff valves shall d. From stationary storage to a pipeline. be provided with protection from overpressure due to thermal expansion of the liquid. Where liquid is trapped in valve cavi 9.2 RATES OF LOADING AND UNLOADING ties, the need for pressure relief shall be considered. 9.2.1 Sizing

8.7 LOCATION, INSTALLATION, AND FLEXIBILITY Pumps and loading devices shall be sized to provide rates OF PIPING, VALVES, AND FITTINGS of flow appropriate to the capacity of the facility. Care shall 8.7.1 Piping shall be provided with adequate flexibility to be taken to ensure that the rates of flow give the operator accommodate the following: enough time to follow the course of loading and unloading at a. Settling of tanks or shifting of foundations. all times and to shut down the facility before tanks are com b. Expansion or contraction of tanks or piping with changes pletely emptied or before they are filled beyond their maxi in temperature. mum filling height. c. Soil movement. d. Cooling or heating of unloading connections, vent connec 9.2.2 Design tions, or loading and unloading headers. The transfer system shall incorporate a means for rapidly 8.7.2 Headers located on piers shall be designed to permit and positively stopping the flow in an emergency. Transfer unrestrained movement of the piping in the direction of systems shall be designed to prevent dangerous surge pres expansion or contraction except at necessary anchor points. sures when the flow in either direction is stopped. 12 API STANDARD 2510

9.3 "TRANSFER, LOADING, AND UNLOADING 9.3.4.2 Installation practices for emergency shutoff' valves EQUIPMENT shall include those specified in 9.3.4.2.1 and 9.3.4.2.2.

9.3.1 Pumps 9.3.4.2.1 When hose or swivel piping is used for liquid or vapor transfer, an emergency shutoff valve shall be installed 9.3.1.1 Pumps may be centrifugal, reciprocating, gear, sub in the fixed piping of the transfer system within 20 linear ft of mersible or may be another type designed for handling LPG. pipe from the end to which the hose or swivel piping is con The design pressure and construction material of the pumps nected. Where the flow is in one direction only, a check-valve shall be capable of safely withstanding the maximum pres may be used in place of an emergency shutoff' valve if the sure that could be developed by the product, the transfer check valve is installed in a dedicated storage vessel fill line equipment, or both. When centrifugal pumps are used, or vapor return line. When two or more hoses or swivel pip mechanical seals are recommended. Positive displacement ing arrangements are used, either an emergency shutoff valve pumps shall have a suitable relief device on the discharge side or a check-valve (for unloading lines only) shall be installed unless other provisions are made for protection of the equip in each leg of the piping. ment. Note: If check valves are used in place of emergency shutoff valves, 9.3.1.2 When submersible pumps are used, each interface the owner/operator should have a program to assure the reliability of between the LPG system and an electrical conduit or wiring these devices. system shall be sealed or isolated to prevent passage of LPG 9.3.4.2.2 The emergency shutoff valves or backflow check to another portion of the electrical installation. See NFPA valves shall be installed in the fixed piping so that any break 59A for further information. resulting from a pull will occur on the hose or swivel piping side of the connection while the valves and piping on the 9.3.2 Compressors plant side of the connection remain intact. This may be Compressors for loading and unloading LPG shall be accomplished by the use of concrete bulkheads or equivalent designed for the maximum outlet pressure to which they may anchorage or by the use of a weakness or shear fitting. Refer be subjected. Each centrifugal compressor discharge connec to NPGA Bulletin 128. tion shall be equipped with a check valve. Each centrifugal 9.3.4.3 Facility boundary limit block valves and check compressor shall be evaluated for conditions that may cause valves shall be provided if the feed or product is transported overpressure, and a relieving device shall be provided if by pipeline. If block valves are manually operated, they shall required. Each positive displacement compressor shall be be accessible during an emergency. equipped with a pressure-relieving device on the discharge side. A suitably sized scrubber or liquid knockout drum shall 9.4 GROUNDING AND BONDING be installed immediately upstream of vapor compressors. The scrubber shall be equipped with a high-liquid-level device to 9.4.1 Static ElectriCity shut down the compressor. Protection from discharge of static electricity is not 9.3.3 Pressure Gauges required when a tank car, a tank truck, or marine equipment is loaded or unloaded through tight (top or bottom) outlets using Pressure gauges shall be provided in enough locations in a conductive or nonconductive hose, flexible metallic tubing, the liquid and vapor lines to enable the operator to monitor or pipe connection because no spark gap exists while product operating pressure and pressure differentials constantly to is flowing (see API RP 2003). ensure safe operation. 9.4.2 Stray Currents 9.3.4 Emergency Shutoff Valves If stray currents are present or if impressed currents are 9.3.4.1 Emergency shutoff valves shall be provided in the used on the loading and unloading systems for cathodic pro loading-unloading system for tank cars, trucks, and marine tection, protective measures shall be taken in accordance with facilities and shall incorporate the following means of closing: API RP2003. a. Manual shutoff' at the installed location. 9.4.3 Lightning Protection b. Manual activation from a location accessible during an emergency. Aboveground metallic LPG storage containers do not require lightning protection. To protect personnel and founda A safety analysis shall be the basis for determining the tions where the piping might not provide grounding, ground need for the following: ing rods shall be provided for tanks supported on a. Automatic shutoff' in the event of an LPG release. nonconductive foundations. See API RP 2003 for additional b. Automatic shutoff through thermal (fire) actuation. infonnation on lightning protection. DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 13

9.5 HOSE AND OTHER FLEXIBLE CONNECTORS mobile tanks shall be equipped with a blowdown or bleeder FOR PRODUCT TRANSFER valve. The valve shall enable the emptying of the hose or pipe connection(s) after the block valves on each side of the hose 9.5.1 Hose or pipe connection(s) have been closed. The blowdown or 9.5.1.1 Hose shall be fabricated of materials resistant to bleeder valve shall be sized and installed so that venting does LPG in both liquid and vapor form. If wire braid is used for not create a hazard. reinforcement, it shall be made from corrosion-resistant material such as stainless steel. 9.7 MARKING OF VALVES IN LOADING AND 9.5.1.2 The correctness of design, construction, and perfor UNLOADING SYSTEMS mance of hose shall be determined. Only hose listed by When more than one product is handled at a loading or Underwriters Laboratories or another nationally recognized unloading rack, the lines shall be marked or designated so testing laboratory shall be used for LPG transfer applications. that the operator can identify the various lines and valves Hose used in marine applications shall be approved by the without having to trace them to their source or destination. U.S. Coast Guard. 9.5.1.3 Hose, hose connections, and flexible connectors 9.8 METERING EQUIPMENT USED IN LOADING used for transferring LPG liquid or vapor at pressures in AND UNLOADING excess of 5 psig shall conform to the criteria specified in When liquid meters are used to measure the volume of 9.5.1.3.1 through 9.5.1.3.3. LPG that is being transferred from one container to another or 9.5.1.3.1 Hose shall be designed for a minimum working that is being transferred to or from a pipeline, the meters and pressure of 350 psig and a minimum bursting pressure of accessory equipment shall be installed in accordance with the 1750 psig. Hose shall be marked "LPG" or "LP-gas" at inter procedures stipulated by API RP 551, and Chapter 5 of the vals of not more than 10ft. API Manual of Petroleum Measurement Standards. 9.5.1.3.2 After the installation of connections, hose assem blies shall be tested to a pressure not less than 700 psig. 9.9 LPG ODORIZATION 9.5.1.3.3 Hose assemblies shall be visually inspected If specified, a stationary LPG storage facility designed to before each use for damage or defects. Hose assemblies shall transfer LPG to tanks, trucks, railroad tank-cars, or marine be tested at least annually at whichever is greater, the maxi containers through loading racks or docks shall have equip mum pump discharge pressure or the relief valve setting. ment that enables the addition of odorant as specified by NFPA 58 and the Transportation Safety Act of 1974, Part 173, 9.5.2 Hose Protection Section 315. Hose shall be protected from the elements and physical damage. Particular attention shall be given to the prevention 10 Fire Protection of potentially damaging ice formation on the corrugations of 10.1 GENERAL metallic hose. Fire protection provisions shall be based on a safety analy 9.5.3 Support of Loading Arms or Hoses sis of local conditions, exposure from or to other sites, avail Provisions shall be made for adequately supporting the ability of a water supply, and effectiveness of fire brigades loading hose or arm. The weight of ice formations on uninsu and fire departments. The analysis shall include possible but lated hoses or arms shall be considered in the design of coun realistic accident scenarios that may occur, including scenar terweights. ios of vapor release, ignition, and fire. For additional informa tion, background, and guidance, see API Publ 25 lOA. 9.5.4 Flexible Pipe Connection Each flexible pipe connection shall be capable of with 10.2 ACCESS FOR FIRE FIGHTING standing a test pressure of 11/2 times the design pressure for The layout of the storage facility, including the arrange its part of the system. ment and location of plant roads, walkways, doors. and oper ating equipment, shall be designed to permit personnel and 9.6 BLOWDOWN OR VENTING OF LOADING AND equipment to reach any area affected by fire rapidly and UNLOADING LINES effectively. The layout shall permit access from at least two Each hose or pipe connection(s) with flexible joints used in directions. Emergency escape as well as access for fire fight the loading and unloading of LPG between stationary and ing shall be considered. 14 API STANDARD 2510

10.3 FIRE WATER USE 10.3.1.9 The fire water system shall be designed to facili tate testing to assure reliability, adequate flow rate, and ade Storage facilities for LPG shall be provided with a fire quate coverage of the protected equipment. water system unless a safety analysis shows this protection to be unnecessary or impractical. See API Publ 2SIOA for addi 10.3.1.10 The fire water systems shall be tested to verify tional information. that their performance is as designed. Since the capacity of the water grid can deteriorate gradually as a result of scale 10.3.1 System Design buildup in the water mains, a Hazen-Williams coefficient no greater than 100 shall be used for unlined steel pipe. The design of the fire water system shall be in accordance with 10.3.1.1 through 10.3.1.10. 10.3.2 Fire Water Application Methods 10.3.1.1 A looped fire water system shall be provided LPG storage vessels shall be protected by water deluge around the storage and handling portions of an LPG facility. systems, fixed monitors, water spray systems, or any combi nation of these systems. Portable equipment may be used but 10.3.1.2 Sufficient isolation valves shall be provided in the shall not be a primary method of water application. fire water grid to prevent loss of the grid due to a single break in the water main. Block valves shall be arranged so that all 10.3.2.1 Water Deluge System parts of the plant can be protected by a portion of the fire water main system when an impaired section is isolated for A water deluge system is a system in which all the water is repair. applied at the top of the vessel and allowed to run down the sides. When a water deluge system is selected for the protec 10.3.1.3 The capacity of the fire water system shall be tion of LPG storage facilities, it shall include the design fea equal to the amount of fire water required to cool the largest tures described in 10.3.2.1.1 through 1O.3.2.I.S. vessel being protected (or if multiple vessels are on a com monly activated fixed deluge or spray system, the capacity of 10.3.2.1.1 The system shall be designed so that under non fire conditions, the water flows evenly over the entire surface the system), plus the amount required to cool adjacent ves sels, plus reserve capacity for up to three additional 2S0-gal of the vessel. The adequacy of the water coverage shall be lon-per-minute cooling streams. Where the capacity of the determined by means of performance tests. fire water system is determined by the requirement for LPG 10.3.2.1.2 If weirs are used to improve distribution, they storage, the system is permitted to be sectionalized to reduce shall be provided with drainage to prevent standing water, the maximum simultaneous requirement for fire water. which may increase corrosion. 10.3.1.4 Pipe used for fire water mains and branch lines to 10.3.2.1.3 Pipe used for main water distribution lines shall hydrants shall be at least 6 NPS in size. Branch lines to del have a diameter of at least 3 in. uge, monitor, or spray systems are permitted to be smaller, 10.3.2.1.4 Top-mounted water distribution nozzles shall be provided hydraulic calculations show that the size selected at least 11;2 in. in size and shall be provided with suitable will supply the design demand at the required pressure. deflectors or weirs to achieve good water distribution. 10.3.1.5 The fire water system shall be functional in all 10.3.2.1.5 The system shall be manually operated from a seasons and shall be capable of delivering 100% of the design safe location that is outside the spill containment area and that rate for at least 4 hours. The fire water system shall be suit is at least SO ft from the vessel being protected. The location ably protected from freezing where necessary. of the actuating valve shall be clearly and prominently 10.3.1.6 The fire water grid shall be designed so that at marked. In locations with unattended or partially attended least half the water required by the single largest incident can operations, consideration shall be given to additional methods be delivered if any single section of the fire water main is lost. of system activation such as automatic or remote operation. When the system is remotely or automatically operated, a 10.3.1.7 Regardless of the fire water application method full-size manually operated bypass valve shall also be pro used, the location of hydrants shall be arranged so that each vided in an accessible, safe location. storage vessel can be reached from at least two directions by at least three cooling streams none of which uses more than 10.3.2.2 Fixed Monitors 300 ft of hose. Fire water monitors permanently connected to the fire 10.3.1.8 The fire water system shall be designed to provide water grid can be used to apply cooling water to the shell of water for cooling to the protected equipment within 60 sec LPG storage vessels. Where protection by means of monitors onds of activation to achieve design water delivery rates is selected, the system shall include the design features within 10 minutes of system activation. described in 10.3.2.2.1 through 10.3.2.2.4. DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 15

10.3.2.2.1 The entire surface of each vessel shall be be 0.25 in. A full-size valved bypass shall be provided. Galva reached with streams from the monitors. nized piping shall be considered downstream of the strainers to reduce the potential for rust scale plugging spray nozzles. 10.3.2.2.2 Each monitor shall be accessible during a fire or shall be remotely activated and controlled. 10.3.2.4 Portable Equipment 10.3.2.2.3 Monitor nozzles shall be adjustable for fog or Portable equipment, such as fire hoses and portable moni straight stream, as required, to provide the most effective cov tors, shall not be used as the only means of protecting erage of the protected vessel. exposed LPG vessels. It is permitted to use portable equip 10.3.2.2.4 In freezing climates, monitors shall be suitably ment when vessels are fireproofed as outlined in 10.7. protected against freezing. 10.3.3 Fire Water Application Rates 10.3.2.3 Water Spray Systems 10.3.3.1 The minimum required fire water application rate A water spray system uses many spray nozzles arranged in depends on the method of application. a grid pattern to distribute the water evenly over the LPG ves sel. When a water spray system is selected for the protection 10.3.3.2 In determining fire water application rates, the of LPG storage facilities, it shall include the design features surface area of the vessel that could be exposed to fire shall be described in 10.3.2.3.1 through 10.3.2.3.6. the surface area of the vessel above the level of the liquid con tents at the vessel's lowest operating level. 10.3.2.3.1 The system shall be designed so that the water is applied evenly over the entire surface of the vessel that may 10.3.3.3 Fixed deluge or water spray systems shall be be exposed to fire. Allowance for rundown is pennitted. The designed to protect against pool fire exposure to the vessel adequacy of the water coverage shall be detennined by per with a minimum fire water application rate of 0.1 0 gallon per fonnance tests. minute per square foot of exposed vessel surface. If there is concern or risk ofa vessel being englllfed by.flame or sll~ject 10.3.2.3.2 The spray system shall be an open-head system, to substantial flame contact, supplemental cooling streams with all nozzles supplied from the top of the supply branch should be provided or the application rate should be line and each branch line shall be from the top of the water increased to 0.25 gpmlft2. distribution main line. Spray orifice size shall be at least 0.25 in .. Larger orifice sizes will reduce the tendency of the noz 10.3.3.4 To compensate for losses due to wind and vapor zles to become clogged. ization that occur before the stream reaches the vessel wall, fire water monitor systems shall be designed to protect 10.3.2.3.3 The system shall be manually operated from a against pool fire exposure to the vessel with a minimum water safe location that is outside the spill containment area and that application rate of 0.20 gallon per minute per square foot of is at least 50 ft from the vessel being protected. The location exposed vessel surface. of the actuating valve shall be clearly and prominently marked. In locations with unattended or partially attended operations, consideration shall be given to additional methods 10.4 FIRE DETECTION SYSTEMS of system activation such as automatic or remote operation. A safety analysis shall be used to determine the need for When the system is remotely or automatically operated, a fire and hydrocarbon detection systems. Where provided, fire full-size manually operated bypass valve shall also be pro and hydrocarbon detection systems shall be arranged to vided in an accessible, safe location. sound their alarms whenever fire or hydrocarbons are present. 10.3.2.3.4 Flush-out connections shall be installed in the It is pennitted to use detection systems to automatically acti system to permit flushing at periodic intervals. Accessible vate isolation or fire protection systems in remote or unat low-point drain connections shall also be provided. tended facilities.

10.3.2.3.5 The sizing of all piping shall be based on 10.5 FIRE EXTINGUISHERS hydraulic calculations. Pipe used for main water distribution lines shall have a diameter of at least 3 in. Pipe used for 10.5.1 Portable fire extinguishers shall be used to extin branch lines to spray heads is pennitted to not be less than guish an LPG fire only after the source of LPG has been shut NPS 3/4 in size. off, to prevent the formation of a hazardous vapor cloud.

10.3.2.3.6 A full-flow strainer with a valved blow-off con 10.5.2 Dry chemical fire extinguishers shall be provided at nection shall be installed in the main feeder line to the spray strategic locations such as those near pumps and loading system. The maximum size of the opening in the strainer shall racks so that they are readily available for operator use. 16 API STANDARD 2510

10.6 FIRE-FIGHTING FOAM 10.B.4 When a vertical vessel is supported by a skirt, the exterior of the skirt shall be fireproofed. Fire-fighting foam shall not be used to extinguish LPG fires. 10.B.S Fireproofing shall be provided on all pipe supports within 50 ft of the vessel and on all pipe supports within the 10.7 FIREPROOFING OF LPG VESSELS spill containment area of the vessel. 10.7.1 Except for remote facilities, which require no pro 10.B.6 To be considered as adequately fireproofed, support tection, fireproofing shall be used to protect vessels if porta structures of concrete or masonry shall meet the criteria of ble equipment is the only means of applying fire water. 10.8.8. 10.7.2 Where fireproofing is used, it shall provide protec 1 0.B.7 Fireproofing is not required for diagonal bracing, tion of the structural steel or LPG vessel for the time period including tie rods, or for redundant members that are not nec required for operation of fire water systems. essary for supporting static loads. 10.7.3 When fireproofing is used, it shall comply with the 10.B.B The thickness of the fireproofing material should be provisions of 10.7.3.1 through 10.7.3.5. equivalent to a fire endurance of 1112 hours per UL 1709 when 10.7.3.1 Outside surfaces of LPG vessels that may be tested on a lOW49 column. exposed to fire shall be covered with a fireproofing material 10.B.9 Fireproofing material shall be suitably protected that is suitable for the temperatures to which the vessel will against weather damage and sealed to prevent water entry. It be exposed. Refer to API Publ 2218 for additional informa shall be resistant to dislodgment by direct impingement of tion on fireproofing. fire water streams. 10.7.3.2 The thickness of the fireproofing material should be equivalent to a fire endurance of 1112 hours per UL 1709 10.9 BURYING AND MOUNDING when tested on a lOW49 column. CAUTION: LPG vessels buried below grade or mounded 10.7.3.3 Thermal insulation used for fireproofing shall be above grade to reduce exposure to an external fire require jacketed with rust-resistant steel. special precautions, careful preparation, and special design features. Adequate protection against corrosion, leaks, and 10.7.3.4 The fireproofing material shall be suitably pro mechanical damage when the vessel is uncovered for inspec tected against weather damage and sealed to prevent water tion shall be provided. Burying and mounding for protection entry. of LPG storage vessels shall be specially engineered and 10.7.3.5 The fireproofing system shall be capable of arranged to meet the provisions of NFPA 58 for buried or withstanding exposure to direct flame impingement and mounded tanks. shall be resistant to dislodgment by direct impingement of fire water streams. Refer to NFPA 58, Appendix G, for fur 10.10 ELECTRICAL INSTALLATIONS AND ther information. EQUIPMENT All electrical installations and equipment shall conform to 10.B FIREPROOFING OF STRUCTURAL the provisions of NFPA 70. Refer to API RP 500 or 505 for SUPPORTS guidance in the classification of electrical areas. 10.B.1 Except for remote facilities, which require no pro tection, structural supports shall be provided with fireproof 10.11 CRITICAL WIRING AND CONTROL ing, as specified in 10.8.2 through 10.8.9. SYSTEMS 10.B.2 Fireproofing shall be provided on the aboveground 10.11.1 Unless the electrical, instrument, and control sys portions of the vessel's supporting structures. The fireproof tems are fail-safe in a fire, these systems-including especially ing shall cover all support members required to support the the wiring used to activate the equipment needed in an emer static load of the full vessel. Fireproofing shall not encase the gency-shall be protected from fire damage. Thus, in areas points at which the supports are welded to the vessel. Refer to where the control wiring used to activate an emergency shut API Publ 2218 for additional information on fireproofing. off valve during a fire could be exposed to the fire, the wiring shall be protected against a IS-minute fire exposure; however, 10.B.3 Fireproofing shall be provided on horizontal vessel if activation of an emergency shutoff valve would not be nec saddles where the distance between the bottom of the vessel essary during any fire to which its wiring could be exposed, and the top of the support structure is greater than 12 in. then protection of the wiring is not required. Where such fireproofing is provided, it shall extend from the support structure to the vessel, except that it shall not encase 10.11.2 Wiring shall be protected by selective routing, the points at which the saddles are welded to the vessel. burying, fireproofing, or a combination of these methods. DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 17

10.12 SAFETY PRECAUTION SIGNS 11.2.1.2 Pressure Storage Appropriate safety precaution signs shall be placed to pro Tanks with design pressures of at least 15 psig shall be vide notification and instructions concerning safety require designed in accordance with the ASME Boiler and Pressure ments and emergency systems. Vessel Code, Section VIIl, Division 1 or 2.

10.13 LIGHTING 11.2.2 Design Pressure

In all storage and operating areas, lighting that is adequate 11.2.2.1 The design pressure of a refrigerated LPG tank is for operations under normal conditions shall be provided. In determined by the product's vapor pressure at the storage addition, lighting that is sufficient to enable safe operations temperature. The set pressure of the pressure-relieving device during an emergency shall be provided. shall be at least 5% greater than the design operating pres sure. 10.14 FENCING 11.2.2.2 The tank section above the maximum liquid level Any LPG storage installation that is not within a fenced shall be designed for a pressure of at least that at which the plant area or otherwise isolated from the public shall be pressure relief valves are to be set and for the maximum partial fenced, and at least two means of exit shall be provided. Exits vacuum that can be developed. All portions of the tank below shall be located so that a single emergency cannot prevent the maximum liquid level shall be designed for at least the egress from any part of the installation. most severe combination of gas pressure (or partial vacuum) cmd static liquid head affecting each element of the tank. 10.15 ROADWAYS 11.2.3 Design Temperature Suitable roadways or other means of access for fire-fight ing equipment such as wheeled extinguishers or fire trucks The design temperature for a refrigerated LPG tank shall shall be provided. Access to LPG handling and storage areas be the lowest of the following: shall be restricted or controlled. a. The lowest temperature to which the tank contents will be refrigerated. 11 Refrigerated Storage b. The lowest shell temperature resulting from cold ambient 11.1 GENERAL conditions, if that temperature is below the refrigerated prod uct temperature. 11.1.1 Scope c. The autorefrigeration temperature of the contents. This section contains specific requirements for refrigerated LPG tanks. Also, unless specifically superseded or expanded 11.3 SITING REQUIREMENTS upon in this section, the requirements of previous sections 11.3.1 Minimum Distance Requirements for apply to refrigerated storage. Refrigerated LPG Tanks

11.1.2 Product Mixing 11.3.1.1 The minimum horizontal distance between the shell of a refrigerated LPG tank and the line of adjoining Loading LPG into a partially full refrigerated LPG tank, property that may be developed shall be 200 ft. Where resi where the LPG being loaded has a different composition than dences, public buildings, places of assembly, or industrial that of the existing tank content, can cause generation of sites are located on adjacent property, greater distances or large quantities of vapor. If this condition can exist, the vapor other supplemental protection shall be evaluated. generation rate can be calculated and included in the sizing of the tank pressure relief valves. As a minimum, the pressure 11.3.1.2 The minimum horizontal distance between the relief valves shall be sized to discharge vapor at a rate no less shells of adjacent refrigerated LPG tanks shall be half the than 3% of the/illl tank liquid capacity in 24 hours. diameter of the larger tank. 11.3.1.3 The minimum horizontal distance between the 11.2 DESIGN REQUIREMENTS shell of a refrigerated LPG tank and the shell of another non 11.2.1 Code Requirements refrigerated hydrocarbon storage facility shall be the largest of the following distances with the exception noted after 11.2.1.1 Low-Pressure Tanks Item d: Tanks with design pressures of less than 15 psig shall con a. If the other storage is pressurized, three quarters of the form to API Std 620. larger tank diameter. 18 API STANDARD 2510 b. If the other storage is in atmospheric tanks and is designed 11.3.5.2 The grading of the area under and surrounding the to contain material with a flash point of 100F or less, one vessel shall direct any leaks or spills to the edge of the diked diameter of the larger tank. area. The grading shall be a minimum of I % slope. Within the c. If the other storage is in atmospheric tanks and is designed diked area, the grading shall cause spills to accumulate away to contain material with a flash point greater than 100F, half from the vessel and any piping located within the diked area. the diameter of the larger tank. 11.3.5.3 Each refrigerated LPG tank shall be provided d. 100 ft. with its own diked area. The holdup of the diked area shall be The minimum horizontal distance between shells need not at least 100% of the volume of the tank. exceed 200 ft. EXCEPTION: More than one tank may be enclosed within the 11.3.2 Siting of Refrigerated LPG Tanks same diked area provided provisions are made to prevent low temperature exposure resulting from leakage from anyone Refrigerated LPG tanks shall not be located within build tank from causing subsequent leakage from any other tank. ings, within the spill containment areas of other flammable or combustible liquid storage tanks as defined in NFPA 30, or 11.3.5.4 When dikes are used as part of the spill contain within the spill containment areas of pressurized storage ment system, the minimum height shall be 1.5 ft, measured tanks. from the inside of the diked area. Where dikes must be higher than 6 ft, provisions shall be made for normal and emergency 11.3.3 Spill Containment access into and out of the diked enclosure. Where dikes must be higher than 12 ft or where ventilation is restricted by the 11.3.3.1 Refrigerated LPG tanks shall be provided with dike, provision shall be made for normal operation of valves spill containment facilities. To prevent the accumulation of and access to the top of the tank or tanks without the need for flammable material under or near a refrigerated LPG tank, the personnel to enter into the area of the diked enclosure that is ground under and surrounding the tank shall be graded to below the top of the dike. All earthen dikes shall have a flat drain any spills to a safe area away from the tank. top section at least 2 ft wide. 11.3.3.2 Spill containment shall be provided by the remote impoundment of spilled material or by the diking of the area 11.4 THERMAL CONSIDERATIONS surrounding the vessel. The tank foundation shall be designed to prevent 32°F or lower temperatures from penetrating the pad and soil. This 11.3.4 Remote Impoundment limitation shall be accomplished by ventilation, insulation, 11.3.4.1 If remote impoundment is to be used for spill con heating systems, or a combination of these. Heating elements, tainment, the remote impoundment facility shall be designed controls, and temperature sensors shall be designed for easy according to the guidelines given in 11.3.4.2 through access and replacement while the tank is in service. Founda 11.3.4.5. tion heating systems shall be provided with temperature mon 11.3.4.2 The grading of the area under and surrounding the itoring and controls. The design of the supporting structure vessels shall direct any leaks or spills to the remote impound shall consider loads resulting from (a) the thermal gradient ment area. The grading shall be a minimum of l % slope. across the supporting structure, foundation, and piling due to the temperature of the contents of the vessel and (b) the ther 11.3.4.3 Toe walls, dikes, trenches, or channels may be mal shock from accidental spills. used to assist in draining the spilled product from the area of the tank to a remote impoundment area. However, the use of 11.5 TANK ACCESSORIES trenches or channels shall be minimized. 11.5.1 PressureNacuum-Relieving Devices 11.3.4.4 The remote impoundment area shall be located at least 50 ft from the vessels draining to it and from any piping 11.5.1.1 Each refrigerated LPG tank shall be provided or other equipment. with at least one pressure-relieving device set to discharge at no more than the maximum allowable working pressure of 11.3.4.5 The holdup of the remote impoundment area shall the tank. be at least 100% of the volume of the largest vessel draining to it. 11.5.1.2 Tanks that may be damaged by internal vacuum shall be provided with at least one vacuum-relieving device set 11.3.5 Diking to open at not less than the partial vacuum design pressure. 11.3.5.1 If diking around the vessel is to be used for spill 11.5.1.3 When a closed inner-tank design is used with an containment, the diked area shall be designed according to outer vapor-tight shell, the outer shell shall be equipped with the guidelines given in 11.3.5.2 through 11.3.5.4. one or more pressure/vacuum-relieving devices. DESIGN AND CONSTRUCTION OF LPG INSTALLATIONS 19

11.5.2 Relief Valve Capacities 11.6.4 Multiple Product Types

Relief devices for tanks designed to conform to API Std When a storage facility handles more than one type of 620 shall be designed in accordance with API Std 2000. product, dedicated loading and unloading lines between tanks Relief devices for tanks designed to confonn to Section VIII and racks shall be considered for each type of product. of the AS ME Code shall be designed in accordance with API RP 520. 11.7 REFRIGERATION SYSTEM

11.5.3 Temperature Indicators 11.7.1 LPG Temperature

Each tank shall be fitted with thermocouples or equivalent The refrigeration system shall maintain the LPG at a tem temperature-indicating devices for use during cool down and perature at which the LPG's vapor pressure does not exceed operations. the tank's design pressure. 11.5.4 Sampling Connections 11.7.2 Sizing If sampling connections are required, they shall be installed on the tank piping rather than on the tank. The sizing of the refrigeration system shall consider the following factors: 11.5.5 Tank Accessory Materials a. Heat flow from the following sources: Low-ductility material such as cast iron, semisteeI, mallea I. The difference between the design ambient tempera ble iron, and cast aluminum shall not be used in any pressure ture and the design storage temperature. retaining accessory parts. 2. Maximum solar radiation. 11.6 PIPING REQUIREMENTS 3. Receipt of product that is wanner than the design tem perature, if such an operation is expected. 11.6.1 Valves 4. Foundation heaters. Shutoff valves and accessory equipment shall be con 5. Connected piping. structed of material suitable for the operating pressure and b. Vapor displacement during filling and vapor return during temperature extremes to which they may be subjected. product transfer.

11.6.2 Insulation 11.7.3 Vapor Handling The insulation shall comprise or contain a vapor barrier An alternate handling method shall be provided for an and shall be weatherproofed. Insulation and weatherproofing excess in the LPG vapor load resulting from insufficient shall be fire retardant. Steel surfaces covered by insulation refrigeration or loss of refrigeration. shall be properly coated to prevent corrosion.

11.6.3 Location 11.7.4 Pressure-Relieving Devices When cold piping is routed below grade, trenches, casing, Refer to API RP 520, Parts I and II, for the proper design of or other means shall be used to permit expansion and contrac pressure-relieving devices and systems for process equipment tion of the piping. used in liquefaction and vaporization facilities,

APPENDIX A-PIPING, VALVES, FITTINGS, AND OPTIONAL EQUIPMENT

A.1 Optional Equipment single emergency situation. Liquid traps in the common header shall be prevented. Other vents, drains, bleeders, and A.1.1 GENERAL pressure relief devices shall not be tied into the common dis Tanks may be fitted with the optional equipment described charge header if back pressures can develop that may prevent in Al.2 through Al.7. Any optional equipment selected for proper functioning of the pressure relief devices on the tank. use shall be suitable for use with LPG and designed for at least See API Publ 251 OA for additional information. the maximum service conditions to which it may be subjected. A.1.6 WATER DRAWOFFS A.1.2 SAMPLING CONNECTIONS Facilities for removing water from LPG storage vessels Sampling connections may be provided on tanks. As an should be provided. These water drawoffs shall be designed alternative, the connections on gauging equipment may be to prevent freezing of water within them. See 6.7.4, 6.7.5, and used for sampling if they are suitably located. Adequate brac API Publ 251 OA for additional information. ing of small connections and piping in sampling lines shall be provided to minimize vulnerability to mechanical damage. A.1.7 WATER FLOOD CONNECTION The inlet piping to sample containers shall be double valved. Sample connection locations should not be under the vessel. Each LPG storage vessel may be provided with a water Connections shall be oriented so that purge vapors do not flood connection. The water flood connection may be pro vided either into the vapor space of the vessel or directly into engulf the operator or approach an ignition source. the product line to the bottom of the vessel. When the water A.1.3 AUTOMATIC AND REMOTE DEVICES flood connection is provided on the product line, the possibil ity of water freezing shall be considered in the design. The Automatic shutoff valves, remotely operated shutoff water flood connection shall extend outside the spill contain valves, automatic warning devices, pump shutdown switches, ment system and shall include (in physical order) a block or a combination of these may be used where tanks are oper valve, a check valve, and provision for connection to the ated remotely, where they receive LPG at a high rate of flow, water system. or for other circumstances in which the designer considers it advisable. Fireproofing of the control systems may be A.2 Location, Installation, and Flexibility required for these devices to be effective during fire exposure. of Piping, Valves, and Fittings See 8.1 1 for additional information. A.2.1 RECOMMENDED PRACTICES A.1.4 STAIRS, LADDERS, WALKWAYS, AND PLATFORMS A.2.1.1 The practices described in A.2.1.2 through A2.1.I1 concerning location, installation, and flexibility of Suitable stairs, ladders, walkways, and platfonns should be piping, valves, and fittings are recommended. provided to allow access to operating valves and equipment. A.2.1.2 The design of header piping and tank loading and A.1.5 COMMON DISCHARGE HEADER unloading connections should be as simple as possible. The number of connections to the storage vessel should be mini Pressure relief valve lines for one or more tanks may be mized. Operating errors increase as the complexity of the pip connected to a common discharge header provided the LPG ing installation and the number of connections increase. is being discharged to a flare. Common discharge headers shall be designed in accordance with API RP 521 and shall A.2.1.3 Shutoff valves that must be used during normal comply with the provisions of 5.1.6.5. Back pressures that operations should be accessible to the operator and should be could develop during relief valve discharge shall be taken into as close to the tanks, pumps, compressors, and other compo account when determining the size of the relief device and of nents as practical. This recommendation should not be con the discharge header. For pilot-operated relief valves dis stmed as discouraging installation of remotely operated charging into a common header, the effects of backflow shutoff valves or other safety devices. should be considered, and a back flow preventer should be A.2.1.4 Headers may be installed on piers, suppolied by provided if required. stanchions, or buried, as specified by the owner. Buried lines CAUTION: Common headers should not be used for venting have the advantage of being protected from fires and explo to the atmosphere. Common discharge headers shall be sized sions but have the disadvantages of the possibility of soil cor for full relief capacity of all tanks that could be involved in a rosion, inaccessibility for inspection, and reduction in 21 22 API STANDARD 2510 flexibility because of the binding action of the earth. Buried A.2.1.10 Low points in piping in which water can accumu lines should be installed below the frost line and protected late should be avoided to the greatest extent practical. In from corrosion. freezing climates, appropriate freeze protection should be provided where low points cannot be avoided. A.2.1.5 Piping should not be laid under concrete floors or slabs. When piping must extend through a concrete wall or A.2.1.11 The second valve in a water drain line should be below a floor slab, it should be protected by a suitable casing. self-closing (that is, it should be a deadman valve).

A.2.1.6 Lines laid under railroad tracks, highways, access A.2.2 REFRIGERATION SYSTEM roads, or loading slabs should be installed in accordance with A.2.2.1 The vapor load resulting from refrigeration may be API RP 1102. handled by one or a combination of the following methods: A.2.1.7 Interconnected piping between tanks or tank acces a. Recovery by a liquefaction system. sories should be installed to permit flexibility in all planes. b. Use as a fuel. For example, loading and unloading headers should not be c. Use as process feedstock. connected to a tank by short, straight rigid piping, regardless d. Disposal by flaring or another safe method. of whether the piping is screwed or welded. Equalizing pip Alternative handling methods shall be provided to dispose ing should not be connected by short, straight piping between of vented vapors in case of failure of the normal methods. If tanks. Vent or relief piping should not have straight piping compressors are used, castings shall be designed to withstand between adjacent tanks. Piping should include adequate a suction pressure of at least 121 % of the tank design pres lengths of pipe, with changes in direction obtained by the use sure. of elbows or bends, to provide for possible vertical and hori zontal movement of the header relative to the tank. A.2.2.2 A refrigerated LPG system should incorporate the following accessories: A.2.1.8 In piping where thermal expansion and contraction are expected to occur, each line should be designed with an a. An entrainment separator in the compressor suction line. b. An oil separator in the compressor discharge line (unless adequate expansion bend, angular offset, or other provision to the compressor is a dry type). allow for linear movement. Expansion bends may be fabri c. A drain and a gauging device for each separator. cated from straight lengths of pipe and welding elbows or U d. A noncondensable gas purge for the condenser. bends. Suitable bellows-type expansion joints, properly e. Automatic compressor controls and emergency alarms to anchored and guided, should be used only where space limi signal at the following times: tations prevent installation of loops or bends. l. When any tank's pressure approaches the maximum or A.2.1.9 To minimize the amount of material that can be minimum allowable tank working pressure or the pressure spilled in the event of a line or equipment failure, emergency at which the vacuum vent will open, or shutoff valves should be installed in long runs of piping that 2. When excess pressure builds up at the condenser are used to carry liquids. because of a failure of the cooling medium.